Which metal is protected by a layer of its own oxide?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$
$H_4\underline{B}_2O_5 + H_2O \longrightarrow H_3BO_3$

$Na_2B_4O_7 \cdot 10H_2O \xrightarrow{\Delta} 2NaBO_2 + B_2O_3 (A) + 10H_2O$. $(A) + MnO \xrightarrow{\Delta} Mn(BO_2)_2 (B)$. $(A)$ and $(B)$ are

Give the industrial preparation for diborane.

Basicity of $H_3BO_3$ is :

State the uses of aluminium and copper.